In U.S. Pat. Nos. 3,226,166, 4,015,751 and 4,280,706 permeable membranes are held in place in pneumatic outlets with mechanical fasteners extending through the permeable membrane and through abutting flanges located on either side of the permeable membrane. Since a fluid medium such as air can pass through the membrane in a direction both perpendicular to the membrane and parallel to or longitudinally of the membrane, the mechanical fastener openings provide a leak path for fluid media through one or both of the flange openings.
To reduce this tendency in one construction the flange portion of the permeable membrane has been painted with a urethane coating in an effort to reduce the flow of fluid media outwardly through the membrane flange portion. However, this has still not reduced flow of fluid media through the flange portion to the extent desired.
The object of the invention is to provide a permeable membrane seal assembly which greatly reduces or eliminates the escape of fluid media through the flange portion of the permeable membrane.